1Heat oven to 425°F. In ungreased 18x13-inch half-sheet pan, toss potatoes and 1 tablespoon oil until potatoes are well coated. Arrange potatoes in single layer in pan.
2Roast uncovered 25 to 30 minutes, stirring after 15 minutes, until potatoes are tender and golden.
3Meanwhile, in blender or food processor, place all remaining ingredients except additional basil. Cover; blend on medium speed about 3 minutes, stopping occasionally to scrape sides, until smooth. Reserve 1/3 cup pesto; refrigerate remaining pesto for later use.
4Toss roasted potatoes with reserved pesto. Garnish with additional basil.